Preparing your photos – merging two scans

I recently received an enquiry from a Findmypast family tree user about uploading scans, and I noticed only half of the birth certificate was scanned. This is not uncommon, since certificates are printed on paper that is awkwardly a little longer than an A4 page, which is even longer than Letter size (for any North American readers), which is the limits of most home scanners.

Don’t despair, there is an easy solution to merging scans into one image file, and I will try to explain the steps here.

Please note, the software I use is a free package that I am familiar with, but there are many other free and paid for packages that you could use. The principles of the process described will be the same.

I have chosen to use Paint.Net. It is simple and free, although they do appreciate donations to help with development costs. It is however a Windows product, so not suitable for Mac or mobile tablet, except Surface. It can be downloaded from here, Warning when you get to the PDN download page, don’t click on the big green button, go to the link on the right.

001a - download paint dot net

After downloading and installing, your ready to go.

First you need to scan you’re document, if you’ve not already done so. Try to line it up against the baseline corner the scanner. It doesn’t matter which way round you scan as we can correct that later. But it helps to get it matching the edge. After you have scanned one side, flip the document 180 degrees around, and scan again. You should now have two images with a distinct area of overlap, albeit one will be upside down.

001d - census combined parts

Open the two images in your image application. Take the one that has the left portion first. If it is upside down, then you need to rotate the image by 180 degrees. This is under the Image menu option. In my example this is not needed for the left portion.

001f - rotate image


Now you need to expand the “canvas”. This is the area that the image covers. Still on the Image menu option, you will see Canvas Size … the ellipsis is a standard Microsoft Windows indicator that a options window will follow.

001g - increase canvas size

The existing size is shown. We will over estimate and increase the size to 1000 pixels wide, and just to cover any slight variation in height, we will increase slightly to 500 pixels. I will also make sure that the size changes are to the right, and above and below, by selecting the middle left square for an anchor position.

001g - new canvas size

I now need to open the second and ensure that is in the right rotation. In my case it is upside down so I sue the rotate 180 degrees mentioned above.

On this second image, now in an upright position, I then choose Select All (CTRL+A) from the Edit menu. And still on the Edit menu, I select Copy (CTRL+C).

I flip back to the first image, use the open image selector at the top, or ALT+TAB.

001h - open image selector

Once the larger first image is back in focus, from the Edit menu, I select the Paste into new layer. This is very important as this will allow you to shift the image into position. Initially, after pasting, the second image will appear anchored to the top left corner and highlighted with a dotted line.

001i - new layer

When you hover over the pasted layer, you will get an arrowed cross. Click down and hold down and then drag your mouse. As you drag the mouse the image will move. If you are careful, you will be able to shift the second image into a position where the overlap covers the original image below.

001j - overlapped new layer

Now you want to trim the excess. I use the rectangle select option from the toolbox. This is the icon in the top left corner of the tools.

001k - toolbox

I start by clicking in the bottom right hand corner of the image where I want to start the trimming. I click down and hold, and drag the mouse all the way to the top left hand corner.

001l - trim select

The from the Image menu, select Crop to selection. You now have the blended image. I normally choose Save As at this point and give it a new name (AND REMEMBER to save as Jpg, not the default Pdn format), so that if I have to repeat the process I can. Once saved, you can close the images and your image application.

You now have a single image from two separate scans. I hope you found this post helpful. If you have any suggestions for improvement, please leave me a comment.

Thank you




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